What is the number letters string (CRC) at the end of the filename for?[edit]

The random, 8 character, number letter string at the end of some filenames is their CRC32 value. It is used to ensure that the file was transferred from one person to another without being corrupted in the process.

For example, the file:
[CAT]_Cooking_fish_howto_video_[CA732D8B].avi

Is suppose to have a CRC32 hash of "CA732D8B". To ensure the copy I downloaded hadn't been corrupted in the process, I would run a hash check on the file and make sure its CRC32 value matches the one found in the file name. Some good hash checkers you could use are: